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Date: Thu, 28 Mar 2024 10:46:50 -0700
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Subject: Re: [PATCH RFC 0/3] mm/gup: consistently call it GUP-fast
To: Mike Rapoport <rppt@kernel.org>, Arnd Bergmann <arnd@arndb.de>
Cc: Vineet Gupta <vgupta@kernel.org>, David Hildenbrand <david@redhat.com>,
 peterx <peterx@redhat.com>, linux-kernel@vger.kernel.org,
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 x86@kernel.org, Ryan Roberts <ryan.roberts@arm.com>,
 Alexander Viro <viro@zeniv.linux.org.uk>, Matt Turner <mattst88@gmail.com>,
 Alexey Brodkin <abrodkin@synopsys.com>
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From: Vineet Gupta <vgupta@kernel.org>
In-Reply-To: <ZgUZCBNloC-grPWJ@kernel.org>
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On 3/28/24 00:15, Mike Rapoport wrote:
> On Thu, Mar 28, 2024 at 07:09:13AM +0100, Arnd Bergmann wrote:
>> On Thu, Mar 28, 2024, at 06:51, Vineet Gupta wrote:
>>> On 3/27/24 09:22, Arnd Bergmann wrote:
>>>> On Wed, Mar 27, 2024, at 16:39, David Hildenbrand wrote:
>>>>> On 27.03.24 16:21, Peter Xu wrote:
>>>>>> On Wed, Mar 27, 2024 at 02:05:35PM +0100, David Hildenbrand wrote:
>>>>>>
>>>>>> I'm not sure what config you tried there; as I am doing some build tests
>>>>>> recently, I found turning off CONFIG_SAMPLES + CONFIG_GCC_PLUGINS could
>>>>>> avoid a lot of issues, I think it's due to libc missing.  But maybe not the
>>>>>> case there.
>>>>> CCin Arnd; I use some of his compiler chains, others from Fedora directly. For
>>>>> example for alpha and arc, the Fedora gcc is "13.2.1".
>>>>> But there is other stuff like (arc):
>>>>>
>>>>> ./arch/arc/include/asm/mmu-arcv2.h: In function 'mmu_setup_asid':
>>>>> ./arch/arc/include/asm/mmu-arcv2.h:82:9: error: implicit declaration of 
>>>>> function 'write_aux_reg' [-Werro
>>>>> r=implicit-function-declaration]
>>>>>     82 |         write_aux_reg(ARC_REG_PID, asid | MMU_ENABLE);
>>>>>        |         ^~~~~~~~~~~~~
>>>> Seems to be missing an #include of soc/arc/aux.h, but I can't
>>>> tell when this first broke without bisecting.
>>> Weird I don't see this one but I only have gcc 12 handy ATM.
>>>
>>>     gcc version 12.2.1 20230306 (ARC HS GNU/Linux glibc toolchain -
>>> build 1360)
>>>
>>> I even tried W=1 (which according to scripts/Makefile.extrawarn) should
>>> include -Werror=implicit-function-declaration but don't see this still.
>>>
>>> Tomorrow I'll try building a gcc 13.2.1 for ARC.
>> David reported them with the toolchains I built at
>> https://mirrors.edge.kernel.org/pub/tools/crosstool/
>> I'm fairly sure the problem is specific to the .config
>> and tree, not the toolchain though.
> This happens with defconfig and both gcc 12.2.0 and gcc 13.2.0 from your
> crosstools. I also see these on the current Linus' tree:
>
> arc/kernel/ptrace.c:342:16: warning: no previous prototype for 'syscall_trace_enter' [-Wmissing-prototypes]
> arch/arc/kernel/kprobes.c:193:15: warning: no previous prototype for 'arc_kprobe_handler' [-Wmissing-prototypes]

Yep these two I could trigger and fix posted [1]

> This fixed the warning about write_aux_reg for me, probably Vineet would
> want this include somewhere else...
>
> diff --git a/arch/arc/include/asm/mmu-arcv2.h b/arch/arc/include/asm/mmu-arcv2.h
> index ed9036d4ede3..0fca342d7b79 100644
> --- a/arch/arc/include/asm/mmu-arcv2.h
> +++ b/arch/arc/include/asm/mmu-arcv2.h
> @@ -69,6 +69,8 @@
>  
>  #ifndef __ASSEMBLY__
>  
> +#include <asm/arcregs.h>
> +
>  struct mm_struct;
>  extern int pae40_exist_but_not_enab(void);

Thx Mike. Indeed the fix is trivial but on tip of tree I still can't
trigger the warning to even test anything. I'm at following with my
other fixes.

    2024-03-27 962490525cff Merge tag 'probes-fixes-v6.9-rc1' of
git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace  

I tried defconfig build as well as the exact config from Linaro report
[2], and/or various toolchains: from snps github, Arnd's crosstool
toolchain.
Granted all of these are linux toolchains - I vaguely remember at some
time, baremetal elf32 toolchain behaved differently due to different
defaults etc.
I have a feeling this was something transient which got fixed up due to
order of header includes etc.

Anyone in the followup email David only reported 2 warnings which have
been tended to as mentioned above - will be sent to Linus soon.

[1]
http://lists.infradead.org/pipermail/linux-snps-arc/2024-March/007916.html
[2]
https://storage.tuxsuite.com/public/linaro/lkft/builds/2eA2VSZdDsL0DMBBhjoauN9IVoK/

Thx,
-Vineet